Method of catalytic hydrogenation of crude benzene derivatives



M. 'H. GWYNN Fen. 1,1938.

muon oF cA'rALYIc HYDROGENATIQN oF cUDE BENZENE DERIvA'rLvEs Filed Se`pt. 17, 1932 FML, 31km ATTORNEYS x Patented Feb. l, 1938v UNITED STATES PATENT oFFlcE METHO) 0F CATALYTIC HYDRGENATION OFCRUDE BENZENE DERIVATIVES Marion H. Gwynn, 4Bound Brook, N. J. Application september 11, 1932, serial Ng. 633,684

4 Claims.

'I'his invention relates to a process for producing -a new type of aromatic solvent by a new process of hydrogenating crude solvent naphbeen found necessary, although it may be de sirable in isolated instances to partially remove thio compounds and even tar acids. If the crude material contains oxygen heterocycles, tar acids.

'may be formed by hydrogenation and may be removed after.

Moreover, whenever lower temperature catalysts, hereinafter termed medium activity catalysts, have been used, the conditions employed were highly uneconomic eitherofcatalyst or time, generally the former. To obtain the best results during hydrogenation, interadjustment and interregulation of catalysts, temperatures and pressures are needed. Heretofore, these fac.

tors have been given as constant, or where a range was specified, it ,was understood that a single temperature or pressure was to have been selected from within that range. By the new process herein disclosed; new hydrogenated products are obtained without loss of yield containing new and useful compounds in substantial quantities.

One object of this invention is the provision of.

a method of'partial hydrogenation preferably in the vapor phase and without pre-purication of the crude starting product. This is dened as a hydroning operation, vas hydrogenating to re-` Fig. 1 .represents a four-stage treatment; and

Fig. 2 represents a six-stage treatment. Y As an example, the raw materials used in this process may dstill between 120 and 240 C., and

include light and heavy solvent naphthas recovered from the coking of coal, drip oil from' carburetted water gas, carbolicoil, crude high flash na.phtha,l and other similar materials whether naturally produced or synthetically derived. It is preferred to use those most commonly and abundantly produced. 'I'hey are crude` light solvent naphtha,v which distills mainly between 12,0 and 180 C., and crude heavy solvent naphtha, which distills mainly between l40'and 240 C. In both cases closer fractions are used, such as the following, but it is to be understood that fractions having the above ranges may be. used and mixtures thereof may be used. My crude mixtures contain reactive polymerizable compounds having an unsaturated side chain or unsaturated side ring, the compounds containing ll Acarbon atoms or less.

- Light Heavy Index of refraction aty Y 20 C 1.502 1.544 Specific gravity at y" C 0.873 0.958. Distillationinitial 130 C. 166 C. Distillation end 165 C. 193 C.

Major saturated vcom- -A ponentsl Dimethyl Trimethyl Benzenes Tetramethyl Benzenes M aj o r unsaturated components i. e., the principal Areactants in my process -..u Styrene Cumarone Indene Naphthalene The hydrogenation is carried `out in the presence of catalysts. Ifused inthe form of powders, the catalysts may be variously prepared by the many methods well known in the art, preferably suspended on porous and comparatively indiierent bases such as kieselguhr, fuller's earth or carborundum. One form of catalyst whichv I maybe used is the permanent type ofcatalyst which maybe said to be. suspended von itself. The preparation and activation of such a catalyst isl described yin U. S. Patent #1,519,035, and

others.

The preferred catalyst'is of the nickel type, such as, nickel oxide with or without the oxides of copper, chromium,'or molybdenum, the whole completely or in part vreduced with hydrogen at the usual temperatures. Copper oxide, with or without chromium, cobalt or silver oxides, with or without reduction. may be used. However, the invention is not to be limited to these alone, as catalysts of lower activity, such as the suldes and oxides cf moiybdenum. chromium, tungsten or manganese, especially v'when promoted with. the oxides or sulfides! of cadmium, silver, cobalt, zinc, copper, tin and magnesium; and even the Acompletely or partially reduced metals, cobalt,

cadmium, silver tln.'may ,be used, always.

The above are medium activity catalysts. Low

activity catalyst like aluminum chloride, carbon or iron are excluded on account of their destructiveness, incompleteness, high temperature and pressure requirements, and the noble metal catalysts, -such as, palladium, platinum, etc. are exeluded on account of their cost and susceptibility to poisoning.

, When a' plurality of catalysts is used in a plurality/of chambers, it ispreferable to use differ- .ent degrees of freshness in the'same metal. the

freshest in the last portion of the hydrogenation. However, different metal catalysts having different activities may be used in the chambers instead of the same metal catalyst.

The temperatures'used in this process may be varied although each activity of catalyst has its corresponding optimumrange. For the following catalysts the range-is approximately as follows:4

nickel type 1D0-160 C.; copper 19o-230 C.; co-

balt, silver and cadmium 260-340 C., but thesev temperatures may be reduced 20 C. with a highly active or fresh form of the catalyst and increased 20 or 30 C. with the low active` or spent form. It was found that by using theglower temperatures, which` is `very unusual, during the Avery early stages oi' the hydrogenation, and the higher temperatures during the later stages that the catalyst lasted muchlonger. The acceleration of this A ascending gradient of temperature is preferably negative.

In vapor phase work, it 1s best to maintain the `pressures substantially constant.

In liquid phase work, pressures can be raised in an ascending gradient, whose acceleration is preferably positive, to counteract afalling rate of hydrogenation and keep the vrate uniform or constant. However, the rateof'hydrog'en absorption may also be maintained uniform or' constant with incre or fresher catalyst and/or higher temperaures.

y While lrvdrogenation can be effected in one Step. it is advantageous to do so in stages, as a means of bettercontrol and o! continuous hydrogenation. When hydrogenatingv in stages, the method may be operated continuously by by-passing and they become spent, while continuing the hydrogenation through the unexhausted chambers and through fresh .v ones, held in reserve. While not limiting the invention to any single method of applying heat to the chambers, the use of a.

counter-current tlow of the heating medium through jacketsabout the chambers, or the use of controlled electric current are given as examples.

If it is.

x20 C. and the tlnal smaller portion in the liquid state, with the temperature grading sharply up and. toward 175 C. Nearly spent nickel can be used at higher temperatures and pressures, but it is then in the class of low active catalysts, being unusually sub-normal. The 1559 C. may'be saidl -to apply to a normal nickel catalyst. While it is possible to use higher temperatures with nickel, the results are' detrimental to the catalyst and product.

The corresponding pressures, however, cannot greater if the activity or the quantity of the cat-I alyst. or the temperatures, become very low.

While the crude liquids may be volatilized for the I vapor phase by any of the methods known to the art, a vaporizer of the carburetor type is preferred to minimize the lossof solvent by heat polymerilzation. A -nickel catalyst is used where it is undel sirable that the side rings be opened and, in general, for more selective hydrogenation, especially at low temperatures' (namely, below 175 C.) and in the liquid phase.

Hydrogenation with nickel at 178 C., in the vapor phase at four atmospheres, produced appreciable lquantities of cyclohexane derivatives,

hydrogen having' gone into thebenzene ring. This is prejudicial to solvent strength and uses excessive hydrogen.

With the crude heavy solvent as a starting product, a high degree of selectivity was attained. A

One example will now'be given using four catalyst umts, the catalysts in this example being of substantially the same composition. A closed vessel is divided into i'our chambers holding separate mckelcatalyst units and these are connected in series and jacket heated by steam. The jackets are so connected that the last receives the fresh steam llrst and the rst receives comparatively cold steam. 'I'he nickel was prepared as described4 in U. S. Patent 1,519,035, reduced at 250 C. vLiquid is continuously pumped into a hot (190 C.) vaporizing chamber. At the outlet Aof this chamber, the vapors are mixed with an reactivating individual chambers of catalyst, as.

excess of hydrogen and the mixtures led overl the first catalyst whose temperature is^ C., thence over the second catalyst at C., over the at 145 C. These temperatures are raised 5, 10, and 20 as the catalyst becomes spent. 'Ihe pressure on the system is about lyslatmospheres, although pressures less than atmospherel (vacuthird `catalyst at- C., and overthe last catalyst um) .may be used. 'Ihe vapors are passed.

through a condenser and lthe excess hydrogen is separated. 'nie condensed productneeds a nishing treatment to make a water-whitesolvcnt. In Fig. l the catalyst chambers Il, having jackets i2 are shown connected together. the first chamber being connected with a vaporizing chamber I4 into which is pumped the liquid to be treated. Atthe outlet of the vaporizlng chamber the vapors are mixed with vhydrogen andthemixture led through the catalyst chambers Il. Steam isusedforheatingthe chambersasshownintliev drawing. and the steam enters the jacket l! of aromas outlet catalyst was fresh the temperatures were kept at about 150 fC. When it had been in use some time, theV temperature was raised to 160 C. 'The specific gravity of the heavy crude starting product was reduced .04, the refractive index was less than .03 and the polymerizable bodies range. -Two examples of the 'resulting product. compared to the ,crude/follows: j g,

` y -V Crude Hydro- 'fined Index of refraction at 20 C. 1.544 1.52 Specific gravity at 15 C 0.958 0.928' Distillation initial 166 C. 163 C. Distillation end f. 193 C. 183 C. Polymerizable content 60%. 5% Aniline point i. -L 23 C.y 21 C.

Index ofy refraction-; 1.502 1.493 Specic gravity 1 0.873 `0.865 Distillation initial 130 C. 128"C.l Distillation end 165 C.. 160 C.

decreased more than fifteen fold by this hydrogenation.

' The sameresults may be obtained in a single reaction chamber in which the temperature may -be substantially constant or may be varied. It is rating chamber for the hydrogen excess, but not a condenseryare needed at the outlet. The liquid' solvent was fed with a proportioning device into the first reaction vchamber with hydrogen gas under 140 pounds pressure. The successive chambers were at 50, 70, 85, 100, 115, and 125 C. These temperatures may be lowered and it is to` be expressly. understood 'that the temperatures given are not to be taken .as invariable. These temperatures were'elevated to 70, 90, 110, 130, 145, and 155 C., when the activity of the catalyst as measured by its production, fell 25%` Alternately the. pressure'could have been increased to 200 lbs. The continuously produced hydroned solvent had absorbed 0.75% hydrogen, its specic gravity had been reduced by 0.03, its refractive index reduced by more than 0.02. 'I'he apparatus shown in Fig.A 2 for carrying out the six-stage operation is similar to the/one shown for the four-stage in that jacketed catalyst chambers are used. However, a condenser is not needed but aV cooler and separating chamber '20 is used. Alsoa known proportioning device 22 is used for feeding the liquid solvent and hydrogen into the first catalyst chamber.

The product of the hy'droiinement described in the liquid phase multistage run, as compared to the original crude aromatic material, contains a higher proportion of hydrogen, has increased solvent strength as measured by the' aniline point method, is 'less dense, and has a lower boiling Polymerizable content '25% l2% To the hydrogenated product as much as an equal volume of such compatible liquids as petroleum, benzine, mineral spirits, xylol, reiined solvent naphtha or rened'high flash napl'itha, may be added depending on the,distillation range and rate of evaporation desired.

An .anti-oxidant such as 1/20 of 1% hydroquinone may also be added to retard the slow yellowing, especially when the hydrofined prod--r uct has not been further treated.

To obtain a purer product the 4vapor phase product resulting from the vapor phase process above given, may be subjected to the liquid phase hydrogenating treatment described in the six stage run or a product only' partially hydrogenated may then be run through a sixstage" liquid phasey treatment similar to that above given but using temperatures of 95, 115,'130, 140, 145 and 150 C. respectivelyinstead of those given in the above example. This is given as one example only as it is Within the contemplation of the invention to subject the product obtained by the vapor phase method to a. liquid phase treatment in which a four stage process or any other `number of. stages may be used. After condensing the treated vapor, it may be caustic Washed before beingsubjected to the liquid phase hydrogenation. The caustic wash :comprises a dilute sodium hydroxide solution.

Insteadv of using only one vcatalyst a plurality 'of diierent catalysts of slightly diierent activity may be used in several stages, all Working at the same pressure and approximately the same temperature. To make the` catalyst for one chamber, mix equimolar portions of cobalt, nitrate, nitric acid, and ammonium chromate; evaporate to apaste, and gently ignite. Fill the first catalyst chamber with the lumps after an extraction with very weak acetic acid. `To make the catalyst for the second chamber follow the above procedure substituting cadmium nitrate for the cobalt. The second chamber is then filled with the second catalyst. Alone, the rst would act most eiiiciently at an average of 260, C. and

. the latter near 230 C. 'I'he corresponding pressures for these catalysts are of quitewide range,

. is nearly spent.

In like manner, three stages might be used, or, ammonium 'molybdate could -be substituted for part or all of the chromate in the above method of preparing the catalyst, and the nitrates by' t ose of other metals such as silver and copper.

With the use of such catalysts and hydrogenating in the liquid. phase, but preferably hydrogenating' with a metallic catalyst in th vapor phase, oxygen het'erocycles mayvbe hydrogenated so as to produce substituted'phenols, such as ortho ethyl phenol from cumarone. Whenever this is done the'r'esulting tar acids are preferably separated before a finishing liquid vphase hydrogenation:

The hydrogen used Ain this process may be pure hydrogen or hydrogen rich gasses essentially free .from carbon oxysuliide, carbon dsulde and like impurities. Atpresent, 'there is a rapidly increasing production of synthetic resins and use of th em as protective coatings. Cool tar solvents have a Vis 'made more usable by refinement to a pennanent water-white color, by the reduction of Vonil'nri-likeodor, by the elimination -of bodies that predpitate in the cold, by improvement of solvent power,andbyreductlon in the speed of evaporation.

Heretofore, the important method for refining crude solvent naphthas, and to a lesser-extent, crudetoluolsfromcoaltarhasbeenwashingwith 66 B sulfuric acid which resiniiies the highly unsaturated components. 'l'his washing is followed, aier separation of the acid sludge, by a caltic wash and a distillation, from which the resin remains in the still.

In the past, this resin formation has been the only known means of refining, although it has always meant a loss of solvent. In a lower boiling range, distilling between 130 and 180 C., the

- yield of refined solvent, chiefly dimethyl benzenes, more commonly known as xylenes, has been about -'15% of the crude solvent n'aphtha. Thelossischieilystyrene. In thenexthigher fraction, distilling approximately-between 150 and m0 C.. the yield varies. It falls as low as 35% of the solvent naphtba. The loss is chiefly coumarone and indene,v which 'are removed as resin, but which, by theherein disclosed process, are converted into stable and useful solvents. The unchanged components consist chiefly of tri and tetra methyibenaenes. The formation of undesired resin is eliminated by hydmeliating the bonds at which polymerization occurs. By controllimthedegree and selectivity ofhydrogerntion itis possible to control the quantity and quality of resin produced.

Asoneresultofthehydrogenationis alower' ing in distillation range, therange of the clude solventisextendedupward. Atichesametimathe` higherboilingfractiomwhicharesolidwhen chilled and are otherwise undesirable, are conver-ted byhydrogenationinto stableliquids with useful solvent properties.. Por example, when naphthalene is prentin the crude solvent, it is converted by hydrogenation from a deleterious solid into tetra-hydro naphthalene. a liquid closely related chemically and compatible with the reiinedsolvent.

as the polymer-lame 'comments of crude- -comprises,va porisingacrude'unmnifiedmixture have the numerom dimcultim involved in hydrougenatimcrudebamnederivativesbeenover- Y 2,100,736 marked superiority as vehicles in such coatings.

come, but new and useful constituents in substantial quantities, have been added and new productscreated.

While it has not been necessary to use special treatmentsof the crude mixtures before hydrogenation, pre-treatments with substances like metallic sodium, or with metallic hydrogenating catalysts before or after reductionV may be used on very low grade crudes or extremes of fractions. l

If the original crude product contains. tar acids, or if it is expedient to'formtar acids during hydregenatiou, such tar acids may be removed by washing the hydrogenated product with dilute aqueous sodium hydroxide with or'without the usual recovery with a strong acid such as sulfuric acid. y

When hydrofininghas not, for reasons of economy, been carried to complete saturation of the bonds at which polymerization occurs, the' unchanged polymerizable bodies may be removed by any of the polymerizing agents known to the,

art and commonly used in rening. Such agents and 66 B. sulfuric acid andV commercially anhydrous aluminum trichloride. To obtain themaximum'. yield of desirable solvent, it is necessary to remove the remaining polymerizable product with a reagent which will not react with the desirable solvent itself. As the hydrogenated bodies of the type formed are easily sulfonated,

the use of 66 B, sulfuric acid is attended by considerable losses. Refining may be completed without sulfonating loss by using in the customary way such agents as aluminum, antimony or stannic chlorides; phosphoric with or without sulfuric acid; micro-porous siliceous compounds, such as fullers earth with or without hydrofluoric acid treatment, silicates in which the aluminum is easily extracted with sulfuric acid, or

silicagels.- v l What I claim is: 1

1. In the art of hydrogenatin'g polymethyl benzenes mixed with crude unsaturated compounds, a method of saturating the unsaturated unpurified compounds withoutvaporization which comprises subjecting the crudeV mixture and hydrogen to the action of a nickel type'catalyst at a relatively low temperature and pressure to hy- `drogenate the unsaturated crude compounds.

raising the temperature gradually so that the average for the 'whole operation isabout 125 C. while increasing the pressure suiliciently to maintain the rate ofabsorption of hydrogen substantially constant.

2. A method of the character described, which containing hydrocarbon benzene derivatives. mixing'anY excess of bydrogen'therewith, passing the mixture .in contact with a series4v of nickel type catalysts while maintaining the tanperaturesunderan ascendinggradientsuchthatthe temperature at the first catalyst portiou'isless than the temperature at the last catalyst portion I to hydrogenate the hydrocarbon benzene derivatives of the crude unpmined mixture. the method being carried out at a relativelylow constant pressure, the average temperatuxeheing substantially 145 C. while a partial pressure of vapor-siem tlum three atmospheres.

la. A method for Aproducing'.mimi yields 'of stable refined solvent which 'comprises'. passing a mixture of hydrogen andthe vapors of Yan unpurified crude mixture ofhydrocarbon'bensene compounds havlngunsaturatedsidechaim .or

rings continuously over a reduced nickel catalyst at a temperature of about 150 C. and at a pressure of about 1% atmospheres such that the major portion of the hydrogen necessary to saturate the side rings or chains is added, then condensing the vapors, then adding the final portion of hydrogen necessary to substantially saturate the side rings or chains in the presence of an active nickel catalyst at a temperature of about 150 C. at a relatively low pressure.

4. In the art of stabilizingcrude, unpuried mixtures of essentially hydrocarbon benzene compounds having unsaturated side chains or unsaturated side rings, the method which comprises passing the vapors of the crude unpuried compounds with an excess of hydrogen through a coniined space and subjecting the vapor mixture to the action of a metal base nickel catalyst at a temperature of about 115 C., then passing such mixture over a second nickel catalyst in the presence of hydrogen at about 130 C. then passing such mixture over a third nickel catalyst at about 140' C. in the presence of hydrogen, and'then passing such mixture over a fourth nickel catalyst at about 145 C. in the presence of hydrogen, the pressure in the stages of the method being substantially constant and being about 1% atmospheres. Y

MARION H. GWYNN. 

